1. Field of Invention
This invention relates generally to window guards or security screens to prevent unauthorized access to a building through its windows, and more particularly to a releasable window guard screen and frame assembly whose hinged screen is fabricated from a single sheet of metal and may be swung out of the frame opening to permit exit from the building through the window.
2. Status of Prior Art
It is common practice to protect the windows of a building, especially those on the ground floor level, from unauthorized entry by means of window guards or grills. Commonly used for this purpose is a guard formed by a framed mesh screen of heavy gauge wire, making it difficult for an intruder to cut the mesh. A wire mesh screen or one made of expanded metal not only prevents intruders from gaining access to the building through the guarded windows, but also serves to shield these windows against breakage.
A permanently-installed window guard has a number of disadvantages, the primary drawback being that in the event of a fire or other emergency, it is not possible to leave the building through the guarded window. One must therefore find another way to escape, and this may not then be available. Another disadvantage of a framed wire mesh screen is that, in time, the screen may become loose or detached from its frame and hence cease to be effective.
Another factor that must be taken into account in window guard design is the extent to which the screen cuts down the amount of light and ventilating air admitted therethrough, as well as the degree to which it reduces visibility. With heavy gauge and relatively thick wire mesh screens, there is a marked reduction in the amount of admitted light and air, and visibility is hindered by the thickness of the screen, particularly when looking through the mesh-guarded window at an oblique angle.
Quite apart from these practical limitations is the fact that wire mesh screen or expanded metal window guards are unappealing from the aesthetic standpoint, for a building having such purely utilitarian window guards presents a prison or factory-like appearance. Conventional security screens for jails and mental institutions are designed to keep individuals in, not out, with little concern for aesthetics. However an otherwise architecturally attractive school building which is a source of pride to the community may be rendered far less presentable should wire mesh or other conventional forms of security screens be installed to guard the windows.
It is also common practice to provide window guards with releasable locking mechanisms which when unlatched permit the screen to be removed or to swing out, thereby permitting exist through the window in case of fire or other emergency.
The ideal locking mechanism for a window guard is one which can be quickly unlatched without difficulty in the event of an emergency, but which when latched makes it very difficult to remove or to swing out the screen, and therefore affords a high degree of security. Prior art locking mechanisms for window guards are either relatively complicated and difficult to release quickly, or of a simple mechanical design that does not offer a high degree of security.
One must also give consideration in window guard design to the need for repair and maintenance, for in time it may be necessary to replace the screen, to paint it or to lubricate the moving parts. With complicated window guards of the prior art type, these parts may be inaccessible or difficult to remove for purposes of maintenance and repair. Window guards are subjected to weathering, and conventional guards whose hinges and other key components are exposed may, as a result of rusting or painting, become difficult to open.
Yet another factor that comes into play when the window guard is of the type in which a screen is supported by a frame attached to the window jamb is that should there exist even a small gap between the screen and the frame, this makes it possible for an intruder to insert a tool in this gap to pry open the screen.
The Pellicore U.S. Pat. No. 2,924,862 shows a window guard for school houses and other applications in which the guard fits within the window jamb. The window guard comprises a welded steel frame formed of a channel member which supports a woven wire mesh. Also provided is a releasable locking means so that the window guard can be opened quickly in the event of an emergency.
The Levin U.S. Pat. No. 2,711,565 shows a window guard in the form of a main frame secured to the window opening, to which is hinged a closure frame supporting a wire mesh, locking means being provided. Kelly, U.S. Pat. No. 3,087,750, shows a window guard in which a framed woven-wire mesh screen is hinged to the side of a window, a lock being provided. These prior art mesh screen arrangements suffer from many of the drawbacks previously discussed.
The Fernandez U.S. Pat. No. 4,634,157 shows a window guard in which bars are supported by a rectangular frame to provide a guard which presents a prison-like appearance. Also prison-like is the bar assembly shown in U.S. Pat. No. 4,771,574 to Stephens, in which a grid formed by bars is held within a frame. Even more prison-like are the window grill of Warwick, U.S. Pat. No. 4,796,384 and the window guard of Hicks et al., U.S. Pat. No. 4,685,316. The patent to Merry, U.S. Pat. No. 4,677,789, shows a window guard in which a frame is secured to a window opening to which is hinged an inner frame having a grate attached thereto.
Also of background interest are the Crotti patent, U.S. Pat. No. 4,294,040, which shows a safety door for buildings formed by two sliding parts, and the Cox patent, U.S. Pat. No. 4,384,428, which discloses a fire escape gate in which a grill or lattice is secured to a hinged frame.
The Hatvany patent U.S. Pat. No. 4,566,222 discloses a one-piece window guard formed of a sheet of metal or plastic having cutouts therein to provide light and ventilation. The side margins of the sheet are rolled to form cylindrical rims, one receiving a hinge bolt and the other a locking bolt. The hinging rim and the locking rim are attached by angle irons to window wall studs.
Hatvany points out that window guards provided with locking mechanisms which can be released from the inside of a building often include springs, flexible cables and other parts which, once installed, are inaccessible for inspection, cleaning, lubrication or replacement, and that should these mechanisms jam in an emergency situation, the consequences may be serious. Hatvany therefore provides a less complicated release mechanism for his window guard.
However, the Hatvany arrangement must be custom tailored to a window jamb of given dimensions in a complicated, costly, through-wall installation, and cannot be fitted into a jamb whose dimensions differ somewhat from the jamb for which it is designed.
None of the prior art window guards satisfies all of the practical and aesthetic requirements mentioned previously which must be taken into account in the design of a window guard that can, without modification, be fitted into window jambs that vary somewhat in their dimensions.